Forming a block diagonal matrix of one certain matrix?

I have a matrix A which is m*n. I want to create a block tridiagonal matrices of size n*m whose diagonals elements are the matrix A.

B=eye(3);
C=ones(2);
S=ones(2);
for i=1:numel(A)
   A(i,i) =repmat(B,i,1)
    A(i,i+1)=repmat(C,i,1)
    A(i,i-1)=repmat(S,i,1)
end

can anyone help me to find the error

[Bandar]

an example will be helpful.

[diadalina]

mY matrix A shoud be like this

A=B C 0000

S B C 000

0 S B C 00

00 S B C 0

where B, C,S are matrices

[Adam Danz]

If that's the example of A, then A cannot be a matrix. Is it a cell array or is the example misleading?

Answer 1

[Matt J]

using interpMatrix (Download)

S=1*ones(2);
B=2*ones(2);
C=3*ones(2);

copies=4; %number of repetitions

L=flip( {S,B,C, zeros(size(B))  } );

idx=full(interpMatrix([1,2,3],2,copies,1))+1;

A=cell2mat(L(idx))

A =

     2     2     3     3     0     0     0     0
     2     2     3     3     0     0     0     0
     1     1     2     2     3     3     0     0
     1     1     2     2     3     3     0     0
     0     0     1     1     2     2     3     3
     0     0     1     1     2     2     3     3
     0     0     0     0     1     1     2     2
     0     0     0     0     1     1     2     2